1. Field of the Invention
The invention relates to a padlock with a U-shaped lock casing, more particularly to a padlock which can minimize malfunctioning thereof due to spring fatigue.
2. Description of the Related Art
A conventional padlock includes a lock casing, a key-operated lock core unit mounted in the lock casing, a shackle bar inserted between opposite shackle mounting portions of the lock casing for retaining an object on the lock casing between the opposite shackle mounting portions, and spring-loaded tumbler means associated operably with the lock core unit for engaging removably the shackle bar. The conventional padlock generally suffers from a disadvantage in that the lock core unit is not removable from the lock casing. As such, in case of spring fatigue that leads to malfunctioning of the padlock, the entire padlock has to be discarded although the lock core unit is still operable.
In Applicant""s co-pending U.S. patent application Ser. No. 09/576,661, there is disclosed a padlock which includes a lock casing having a core receiving space, a latch recess communicated with the core receiving space, a first shackle insert hole, a second shackle insert hole aligned with the first shackle insert hole, and a slide channel communicating the second shackle insert hole with the latch recess. A lock core unit includes a latch member extending into the latch recess and rotatable inside the latch recess between locking and unlocking positions. A shackle bar extends into the first and second shackle insert holes. A catch member is disposed slidably in the latch recess, and has a first abutment wall formed with a shackle engaging projection that extends into the slide channel, a second abutment wall spaced apart from the first abutment wall, and a latch cavity defined between the first and second abutment walls for extension of the latch member thereinto. The latch member pushes the first abutment wall to enable the shackle engaging projection to project into the second shackle insert hole and engage the shackle bar when the latch member is disposed in the locking position. The latch member pushes the second abutment wall to enable the shackle engaging portion to retract into the slide channel and disengage from the shackle bar when the latch member is disposed in the unlocking position.
As shown in FIGS. 2 and 3 of the aforementioned co-pending Patent application, the latch member has a latch base formed with a slide passage, a latch body mounted inside the slide passage, and a biasing spring provided in the slide passage for biasing the latch body to extend outwardly of the slide passage and to project from the latch base. In case the biasing spring experiences spring fatigue under a locking state of the padlock, the lock core unit cannot be operated for retracting the latch body and rotating the latch member to the unlocking position. As a result, the padlock does not work and might need to be destroyed for removal from the object locked thereon.
Therefore, the object of the present invention is to provide a padlock which can effectively minimize malfunctioning thereof due to spring fatigue.
Accordingly, the padlock of the present invention includes a lock casing, a key-operated lock core unit, a shackle bar, and a catch member. The lock casing has first and second end surfaces which are opposite to each other in a longitudinal direction, and includes a lock core mounting portion adjacent to the first end surface, a latch receiving portion adjacent to the second end surface, and first and second shackle mounting portions. The lock core mounting portion is formed with a core receiving space that extends in the longitudinal direction from the first end surface toward the second end surface. The latch receiving portion is formed with a latch recess communicated with the core receiving space. The first shackle mounting portion extends from the lock core mounting portion in a first transverse direction transverse to the longitudinal direction, and is formed with a first shackle insert hole. The second shackle mounting portion extends from the latch receiving portion in the first transverse direction, and is opposite to the first shackle mounting portion. The second shackle mounting portion is formed with a second shackle insert hole that is aligned with the first shackle insert hole in the longitudinal direction. The second shackle mounting portion is further formed with a slide channel that extends in the first transverse direction to communicate the second shackle insert hole with the latch recess. The lock core unit includes a cylindrical lock core formed with a keyhole and disposed in the core receiving space. The lock core is adapted to be rotated inside the core receiving space upon insertion of a corresponding key into the keyhole. The lock core has one end disposed adjacent to the latch recess. The lock core unit further includes a latch member connected to said one end of the lock core and extending into the latch recess. The latch member is rotatable inside the latch recess between locking and unlocking positions when the corresponding key is operated. The latch member has an end face which is transverse to an axis of the lock core and which is formed with a pin hole that is eccentric to the axis of the lock core. The shackle bar has a first end extending into the first shackle insert hole, and a second end extending into the second shackle insert hole. At least one of the first and second ends is removable from a corresponding one of the first and second shackle insert holes. The catch member is disposed slidably in the latch recess, and has a shackle engaging end portion for engaging the shackle bar, and a latch engaging end portion opposite to the shackle engaging end portion and formed with a pin that extends rotatably into the pin hole in the latch member for engaging the latch member such that the catch member is movable between locking and unlocking positions when the latch member moves between the locking and unlocking positions. The shackle engaging end portion of the catch member extends into the second shackle insert hole via the slide channel for engaging the shackle bar when the catch member is moved to the locking position. The shackle engaging end portion is retracted into the slide channel for disengaging from the shackle bar when the catch member is moved to the unlocking position.